DOCSLIB.ORG

N95- 161 99 N95-,1@00 N95- 16201

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
N95- 161 99 N95-,1@00 N95- 16201 36 Mars Pathfinder tanding Sire Workshop N95- 16199 MAJA VALLES AND THE CHRYSE OUTFLOW COMPLEX allow investigations of Mawrth Valles. The region near the mouth SITES. J. W. Rice, Department of Geography, Arizona State of Mawrth Valles would be of interest because this area contains p \ University. Tempe AZ 85287, USA. material that appears to have been dissected, thus exposing the stratigraphy of what may possibly be deltaic sediments. c Mala Valles Region: This candidate landing site is located at 19"N, 53.5"W near the mouth of a major outflow channel, Maja N95-,1@00-* I Valles, and two "valley network" channel systems, Maumee and Vedra Valles. This region has been mapped in detail by Rice and dTEVALLES SITE. J. W. Rice, Department of Geography, De Hon and is in press as a USGS 1:5oO,OOO scale geologic map. Arizona State University, Tempe AZ 85287, USA. The advantages to this site are the following: Two distinct channel forms (outflow and dendritic valley network) in one location. These This site is located at 16ON, 177OW on the flood plains of Marte channels were formed by different processes. The outflow channels Valles, which is perhaps the youngest channel system on Mars. are believed to have formed by catastrophic release of water and the However, the coordinates for the landing site are flexible. Moving valley networks by surface runoff and or sapping. The ideal landing the site more to the southwest would allow investigations of pos- site, if it could be pinpointed, would be on the fan delta complex sible lacustrine sediments. The channel extends for about 3000 km located at the terminus of the three channels (Maja, Maumee, and from southeastern Elysium Planitia into western Amazonis Planitia. Vedra Valles). The fan delta complex would be a fairly smooth This system appears to originate within the knobby cratered mate- surface with shallow slopes. rial around Cerberus Rupes, a set of en echelon fractures that extend Water was impounded behind the wrinkle ridge system, Xanthe for more than 1000 km. Crater counts indicate that this system is Scopulus, forming a temporal lake. This paleolake bed would also Amazonian in age. This channel may have also acted as a spillway present itself as a safe landing site, perhaps similar to playas. Once between paleolakes located in Elysium and Amazonis Planitia. The the wrinkle ridges were breached the water flowed northeastward young age of this channel warrants investigation because of climatic in the direction of the Viking I lander, some 350 km away. implications for fluvial activity in recent geologic time. The paucity Objectives to be analyzed in this region are (I) origin and of craters makes this an excellent site in terms of safety require- paleohydrology of outflow and valley network channels, (2) fan ments. Detailed work by Tanaka and Scott indicate that embayed delta complex composition (this deposit located in this area is one craters larger than 1 km diameter appear embayed by the channeled of the few deposits identified at the mouths of any channels on the plains unit, suggesting that it is only tens of meters thick. This planet), and (3) analysis of any paleolake sediments (carbonates, material contributed to the resurfacing of the northern lowlands of evaporites). Another advantage to this area will be any blocks and the planet. Some of the objectives stated previously for the Maja boulders that were plucked out and carried along the 1600-km Valles Region would also apply to this site (grab bag of rock types, course of Maja Valles. These samples would provide a virtual grab etc.). This site is below the 0-km datum, located at 16ON. and has bag of lithologies. For example, the oldest mappable rock unit (Nb. the young channeled plains, bars, terraces, and streamlined albedo Noachian basement material) and the Hesperian ridged plains (Hr) patterns located within the 150-km landing error ellipse. Resolution are cut by Maja Valles before it empties into Chryse. It can be argued coverage in some areas is as high as 13 dp. that we will not know their exact location, which is true, but it will 1- L N95- 16201 provide us with information about the variety of rock types on Mars .-; :' . /y by only landing in one site. Other questions to be investigated in the area are the origin of wrinkle ridges by viewing ridge walls that were ALPHA PROTON X-RAY SPECTROMETER. R. Riederl, incised by the outflow, streamlined islanddbars; whether they are H. Wbke', and T. Ekonomou2, IMax-Planck-Institut fiir Chemie. erosional or depositional, and if the location pennits view channel Mainz, Germany, Wniversity of Chicago, Chicago IL 60637, USA. wall stratigraphy, fan delta stratigraphy, and perhaps send the rover up a channel mouth near the end of its mission. Mars Pathfinder will carry an alpha-proton X-ray spectrometer This site is below the 0-km elevation datum, within the latitude (APX) for the determination of the elemental chemical composition restrictions (19ON), and all the objectives stated above are within of martian rocks and soils. The instrument will measure the concen- the 150-km landing error ellipse. This region is also imaged at tration of all major and some minor elements, including C. N. and resolutions of 40-50 m/p. 0, at levels above typically 1%. The Chrsye Outflow Complex Region (Ares, Tiu, Mawrth, The method employed consists of bombarding a sample 50 mm Simud, and Shalbatana Valles): The overall philosophy and in diameter with alpha particles from a radioactive source (50 mCi objectives described above for the Maja Valles region apply here as of 240Cm) and measuring (I) backscattered alpha particles (Ruther- well. The primary objectives here would be outflow channel dynam- ford backscatter = RBS mode), (2) protons from A( ,p)B reactions ics (paleohydrology) of five different channel systems. One question (proton mode) and (3) characteristic X-rays emitted from the sample to be answered might be whether all outflow channels are of the (X-ray mode). In RBS mode all elements with atomic mass greater same origin and type. They are probably all somewhat different in than four are registered, thus permitting normalization of results to terms of duration, age, source, and perhaps even origin. The grab 100% concentration. This feature permits accurate quantitative bag philosophy of various rock types being deposited near channel analysis independent (within limits) of the actual measurement mouths would apply here also. The site is located at ISON. 35OW. geometry. Data obtained from proton and X-ray modes are used to However, the longitudinal coordinate can be relaxed or slid farther enhance selectivity of the RBS mode for the rock-forming elements to either side of 35OW. Sliding the ellipse farther to the east would Mg, AI, and Si and for heavier elements (K and Ca. Fe-group): .
Load more

Recommended publications
  • Episodic Flood Inundations of the Northern Plains of Mars
    www.elsevier.com/locate/icarus Episodic flood inundations of the northern plains of Mars Alberto G. Fairén,a,b,∗ James M. Dohm,c Victor R. Baker,c,d Miguel A. de Pablo,b,e Javier Ruiz,f Justin C. Ferris,g and Robert C. Anderson h a CBM, CSIC-Universidad Autónoma de Madrid, 28049 Cantoblanco, Madrid, Spain b Seminar on Planetary Sciences, Universidad Complutense de Madrid, 28040 Madrid, Spain c Department of Hydrology and Water Resources, University of Arizona, Tucson, AZ 85721, USA d Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA e ESCET, Universidad Rey Juan Carlos, 28933 Móstoles, Madrid, Spain f Departamento de Geodinámica, Universidad Complutense de Madrid, 28040 Madrid, Spain g US Geological Survey, Denver, CO 80225, USA h Jet Propulsion Laboratory, Pasadena, CA 91109, USA Received 19 December 2002; revised 20 March 2003 Abstract Throughout the recorded history of Mars, liquid water has distinctly shaped its landscape, including the prominent circum-Chryse and the northwestern slope valleys outflow channel systems, and the extremely flat northern plains topography at the distal reaches of these outflow channel systems. Paleotopographic reconstructions of the Tharsis magmatic complex reveal the existence of an Europe-sized Noachian drainage basin and subsequent aquifer system in eastern Tharsis. This basin is proposed to have sourced outburst floodwaters that sculpted the outflow channels, and ponded to form various hypothesized oceans, seas, and lakes episodically through time. These floodwaters decreased in volume with time due to inadequate groundwater recharge of the Tharsis aquifer system. Martian topography, as observed from the Mars Orbiter Laser Altimeter, corresponds well to these ancient flood inundations, including the approximated shorelines that have been proposed for the northern plains.
    [Show full text]
  • 0 Lunar and Planetary Institute Provided by the NASA Astrophysics Data System STREAMLINED FORMS Baker, V
    STREAMLINED EROSIONAL FORMS OF KASEI AND MAJA VALLES, MARS. Victor R. Baker and R. Craig Kochel, Departnsent of Geological Sciences, The University of Texas at Austin, Austin, Texas 78712. U'e have now completed measurements on 95 streamlined uplands or "teardrop shaped islands:' in two major Martian outflow channels, Kasei and Maja. The data were obtained by techniques previously described by Baker and Kochel (1, 2). They are compared to measurements on 137 streamlined hills and bars in the Channeled Scabland of eastern Washington (3). The three physical parameters that proved easiest to measure from Viking orbital photographs were length L (km), measured parallel to the inferred flow direction; width W (km ), measured as the maximum width of 9e streamlined form perpendicular to the inferred flow direction; and area A (kin ), measured with a polar planimeter. We only measured the best developed streamlined shapes, ie. shapes for which fluid dynamic considerations dictate minimum flow separation in the responsible erosive fluid. Figures 1, 2, and 3 show that all the data conform in a general manner to the following simple model: There is, however, a tendency for the Martian forms, especially in Maja Valiis, to be slightly more elongate than their scabland counterparts (L=4W). This is confirmed statistically by the "best-fit" regressions summarized in Table 1. Considerations of pressure drag and skin resistance, discussed by Baker and Kochel (21, explain the more elongate Maja forms in terms of the lower frictional drag coef- ficients that prevail at higher Reynold's numbers. As the L/W ratio increases, pressure drag is reduced until it becomes eqvl to the total skin resistance.
    [Show full text]
  • Erosive Flood Events on the Surface of Mars: Application to Mangala and Athabasca Valles Alistair Simon Bargery, Lionel Wilson
    Erosive flood events on the surface of Mars: application to Mangala and Athabasca Valles Alistair Simon Bargery, Lionel Wilson To cite this version: Alistair Simon Bargery, Lionel Wilson. Erosive flood events on the surface of Mars: application to Mangala and Athabasca Valles. Icarus, Elsevier, 2011, 212 (2), pp.520. 10.1016/j.icarus.2011.01.001. hal-00734590 HAL Id: hal-00734590 https://hal.archives-ouvertes.fr/hal-00734590 Submitted on 24 Sep 2012 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Accepted Manuscript Erosive flood events on the surface of Mars: application to Mangala and Atha‐ basca Valles Alistair Simon Bargery, Lionel Wilson PII: S0019-1035(11)00002-9 DOI: 10.1016/j.icarus.2011.01.001 Reference: YICAR 9680 To appear in: Icarus Received Date: 20 June 2010 Revised Date: 28 December 2010 Accepted Date: 3 January 2011 Please cite this article as: Bargery, A.S., Wilson, L., Erosive flood events on the surface of Mars: application to Mangala and Athabasca Valles, Icarus (2011), doi: 10.1016/j.icarus.2011.01.001 This is a PDF file of an unedited manuscript that has been accepted for publication.
    [Show full text]
  • 3 a Review of Open-Channel Megaflood Depositional Landforms
    3 A review of open-channel megaflood depositional landforms on Earth and Mars PAUL A. CARLING, DEVON M. BURR, TIMOTHY F. JOHNSEN and TRACY A. BRENNAND Summary develop specific landforms in given environments. Simi- Catastrophic out-bursts of water from lakes larly, the effect of large sediment loads on the hydraulics impounded by glacial ice or debris such as moraines have has not been explored widely (Carling et al., 2003) and there caused large freshwater floods on Earth in recent times at is little knowledge of the relationship of the hydraulics to least back to the Quaternary. Resultant large-scale deposi- the stratigraphic associations, although the spatial variation tional sedimentary landforms are found along the courses in the former can be modelled (e.g. Miller, 1995; Clarke of these floodwaters. On Mars, similar floods have resulted et al., 2004) and the latter may be well recorded (e.g. from catastrophic efflux of water from within the Martian Sridhar, 2007; Duller et al., 2008). crust. This latter conclusion is based on large-scale and Here, is presented an overview of some key con- mesoscale landforms that appear similar to those identi- siderations relevant to identifying alluvial landforms on fied in flood tracts on Earth. Both on Earth and on Mars, Earth and other planets. These considerations include the these landforms include suites of giant bars – ‘streamlined mode of sediment transport and the granulometry of the forms’ – of varying morphology that occur primarily as deposits. This synopsis includes depositional landforms longitudinal features within the floodways as well as in and the known conditions of formation and serves as both a flooded areas that were sheltered from the main flow.
    [Show full text]
  • Mars Pathfinder Landing Site Workshop Ii: Characteristics of the Ares Vallis Region and Field Trips in the Channeled Scabland, Washington
    /, NASA-CR-200508 L / MARS PATHFINDER LANDING SITE WORKSHOP II: CHARACTERISTICS OF THE ARES VALLIS REGION AND FIELD TRIPS IN THE CHANNELED SCABLAND, WASHINGTON LPI Technical Report Number 95-01, Part 1 Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113 LPI/TR--95-01, Part 1 "lp MARS PATHFINDER LANDING SITE WORKSHOP II: CHARACTERISTICS OF THE ARES VALLIS REGION AND FIELD TRIPS IN THE CHANNELED SCABLAND, WASHINGTON Edited by M. P. Golombek, K. S. Edgett, and J. W. Rice Jr. Held at Spokane, Washington September 24-30, 1995 Sponsored by Arizona State University Jet Propulsion Laboratory Lunar and Planetary Institute National Aeronautics and Space Administration Lunar and Planetary Institute 3600 Bay Area Boulevard Houston TX 77058-1113 LPI Technical Report Number 95-01, Part 1 LPI/TR--95-01, Part 1 Compiled in 1995 by LUNAR AND PLANETARY INSTITUTE The Institute is operated by the University Space Research Association under Contract No. NASW-4574 with the National Aeronautics and Space Administration. Material in this volume may he copied without restraint for library, abstract service, education, or personal research purposes; however, republication of any paper or portion thereof requires the written permission of the authors as well as the appropriate acknowledgment of this publication. This report may he cited as Golomhek M. P., Edger K. S., and Rice J. W. Jr., eds. ( 1992)Mars Pathfinder Landing Site Workshop 11: Characteristics of the Ares Vallis Region and Field Trips to the Channeled Scabland, Washington. LPI Tech. Rpt. 95-01, Part 1, Lunar and Planetary Institute, Houston. 63 pp.
    [Show full text]
  • Reappraisal of the Stratigraphic Position of Light Toned Materials in Juventae Chasma, Mars
    Lunar and Planetary Science XLVIII (2017) 2170.pdf Reappraisal of the Stratigraphic Position of Light Toned Materials in Juventae Chasma, Mars. Ranjan Sarkar1, Kenneth S. Edgett2, Pragya Singh1, Alok Porwal1, 1Geology and Mineral Resources Group, CSRE, Indian Institute of Technology, Bombay, ([email protected]; [email protected]); 2Malin Space Science Systems, Inc.,P.O.Box 910148, San Diego,CA 92191-0148 USA, ([email protected]). Introduction: The stratigraphic position of light toned Average layer thicknesses are similar for A and C (~ 2-3 m) materials in Juventae Chasma on Mars is revaluated. but significantly different for B (> 80m) [7]. Deformational Juventae Chasma is an isolated box canyon located north- features are also different for Mound B compared to the rest east of the main Valles Marineris canyon system. It contains [8]. Layers from one mound cannot be traced across the four separate mounds of light-toned layered material labeled voids between them. These observations indicate that the A, B, C, and D (Fig. 1). Layering style varies from layered, four mounds may not have been parts of a singular stratal bedded, terraced, cliff-and-bench to massive. package, unless subsequent intense deformation and erosion Mineralogically these are hydrated sulphate bearing [1,2,3] have obscured their common traits. This seems infeasible although other minerals not captured in VNIR-SWIR spectra unless there has been some overburden to exert pressure. could also be present. Features such as jagged edges, Moreover, there are widespread occurrences of isolated kilometres-tall mounds, steep escarpments, sharp crested outcrops of light toned material distant from the main spur-and-gullies, wind-cut cuspate ridges and yardangs, and mounds (Fig.
    [Show full text]
  • Advances in Reconstructing the Geologic History of the Chryse Region Outflow Channels on Mars
    Lunar and Planetary Science XXXV (2004) 1770.pdf ADVANCES IN RECONSTRUCTING THE GEOLOGIC HISTORY OF THE CHRYSE REGION OUTFLOW CHANNELS ON MARS. K. L. Tanaka1 and J. A. Skinner, Jr.2, 1 U.S. Geological Survey, 2255 N. Gemini Dr., Flagstaff, AZ 86001, 2Environmental Geomatics, 719 New Road, Raleigh, NC 27608, [email protected]. Introduction: We have updated our geologic mapping the large outflow channels as well as dissection from of the northern plains of Mars, based on analysis of Mars numerous sinuous channels occurring sporadically Odyssey (MO) Thermal Emission Imaging System throughout the Noachian rocks surrounding Chryse basin. (THEMIS) images and Mars Global Surveyor (MGS) Mars An increasing number of these channels are being Orbiter Laser Altimeter (MOLA) and Mars Orbiter Camera recognized in THEMIS data. (MOC) data. One of our objectives in the mapping has been Chryse unit 2, N(5) = 108±22. This unit embays Chryse the reconstruction of Chryse region outflow channel unit 1 and makes up higher-standing plains outcrops on the activity. Here, we present new findings that bear on margins of Chryse Planitia and is inferred to form some channeling history, the northern plains ocean hypothesis, channel bars in northern Chryse. In northwestern Chryse, and hematite formation in Aram Chaos. the unit appears to be sourced from fractures and troughs Background: The Chryse outflow channels consist near lower Kasei Valles. In southwestern Chryse, the unit primarily of, from west to east, Kasei, Maja, Simud, Tiu, appears to be associated with Maja Valles, including Ares, and Mawrth Valles that debouch into Chryse and secondary channels that spilled over the highland margin at southern Acidalia Planitia (Fig.
    [Show full text]
  • Phyllosilicates and Sulfates on Mars
    Phyllosilicates and Sulfates on Mars Case Studies from Terra Cimmeria and Valles Marineris Inauguraldissertation zur Erlangung des Grades eines Doktors der Naturwissenschaften am Fachbereich Geowissenschaften der Freien Universität Berlin Vorgelegt von Lorenz Wendt Berlin, 2012 I Ersttgutachter: Prof. Dr. Ralf Jaumann Fachbereich Geowissenschaften Institut für Geologische Wissenschaften Fachrichtung Planetologie und Fernerkundung und Deutsches Zentrum für Luft- und Raumfahrt DLR Institut für Planetenforschung, Abteilung Planetologie Zweitgutachter: Prof. Dr. Stephan van Gasselt Freie Universität Berlin Fachbereich Geowissenschaften Institut für Geologische Wissenschaften Fachrichtung Planetologie und Fernerkundung Datum der Disputation: 13. Juli 2012 III Eidesstattliche Erklärung Hiermit erkläre ich, die vorliegende Arbeit selbständig und nur unter Verwendung der angegebenen Quellen und Hilfsmittel erstellt zu haben. Lorenz Wendt V Danksagung Ich möchte zuallererst Herrn Prof. Neukum meinen Dank aussprechen. Seine High Resolution Stereo Camera (HRSC), die er mit viel Durchhaltevermögen nach dem Absturz der Mars 96 Mission auf Mars Express auf die Reise schickte, gab mir überhaupt erst die Möglichkeit, mich an der Freien Universität Berlin mit der Geologie des Mars zu beschäftigen. Herr Prof. Neukum hat mir damit die Tür zur Planetenforschung geöffnet, und mir auch in vielerlei anderer Hinsicht Möglichkeiten zur wissenschaftlichen Weiterentwicklung eröffnet. Herrn Prof. van Gasselt danke ich für die Begutachtung der vorliegenden Arbeit, die fachlichen Diskussionen und die kritische Durchsicht meiner Manuskripte, sowie die menschliche Unterstützung an manch einem schwierigen Punkt, der sich im Lauf der Arbeit an dieser Dissertation ergab. Und natürlich danke ich ihm für die viele Mühe im Hintergrund, die er sich mit der Betreuung der wissenschaftlichen Anträge gemacht hat, aus denen viele meiner Kollegen und auch ich ihren Lebensunterhalt bestritten haben.
    [Show full text]
  • Geologic Map of the Mtm 25047 and 20047 Quadrangles
    U.S. DEPARTMENT OF THE INTERIOR Prepared for the GEOLOGIC INVESTIGATIONS SERIES I–2693 U.S. GEOLOGICAL SURVEY NATIONAL AERONAUTICS AND SPACE ADMINISTRATION ATLAS OF MARS: MTM 25047 AND 20047 QUADRANGLES 45° 46° 48 North 47° 50° 49° ° Hchp Channel flood-plain material—Forms smooth, low-lying plains adjacent to and Schultz, 1985; Watters, 1993). Because ridges may accumulate strain over long geologic Clark, B.C., Baird, A.K., Weldon, R.J., Tsusaki, D.M., Schnabel, L., and Candelaria, M.P., 48° HNpl 27.5° grooved channel units (Hch and AHch). Forms terraces and slopes adjacent to periods of time, the smaller size of ridges in the younger ridged plains material compared with 1982, Chemical composition of martian fines: Journal of Geophysical Research, v. 87, p. 27.5° remnant islands of ridged plains units and in places surrounds areas of channel ridges developed on the older ridged plains material may reflect a shorter time period over 10069–10082. cm N floor unit (Hch). Interpretation: Flood-plain unit indicating high-water which strain has continued to accumulate over buried ridges. Estimates of younger ridged Craddock, R.A., and Zimbelman, J.R., 1989, Yorktown and Lexington as viewed by the Viking Hr c p Hch overflows from main channels of early flood events. Emplaced at plains material thickness of several hundred meters exceed the measured heights of typical 1 Lander, in Abstracts of papers presented at the Twentieth Lunar and Planetary Science approximately the same time as channel floor unit (Hch). Local evidence for wrinkle ridges (Plescia and Golombek, 1986), so the complete burial of existing ridges may Conference, 1989, Lunar and Planetary Institute, Houston, p.
    [Show full text]
  • Geologic Map of the Northern Plains of Mars
    Prepared for the National Aeronautics and Space Administration Geologic Map of the Northern Plains of Mars By Kenneth L. Tanaka, James A. Skinner, Jr., and Trent M. Hare Pamphlet to accompany Scientific Investigations Map 2888 180° E E L Y S I U M P L A N I T I A A M A Z O N I S P L A N I T I A A R C A D I A P L A N I T I A N U T O P I A 0° N P L A N I T I A 30° T I T S A N A S V 60° I S I D I S 270° E 90° E P L A N I T I A B O S R E A L I A C I D A L I A P L A N I T I A C H R Y S E P L A N I T I A 2005 0° E U.S. Department of the Interior U.S. Geological Survey blank CONTENTS Page INTRODUCTION . 1 PHYSIOGRAPHIC SETTING . 1 DATA . 2 METHODOLOGY . 3 Unit delineation . 3 Unit names . 4 Unit groupings and symbols . 4 Unit colors . 4 Contact types . 4 Feature symbols . 4 GIS approaches and tools . 5 STRATIGRAPHY . 5 Early Noachian Epoch . 5 Middle and Late Noachian Epochs . 6 Early Hesperian Epoch . 7 Late Hesperian Epoch . 8 Early Amazonian Epoch . 9 Middle Amazonian Epoch . 12 Late Amazonian Epoch . 12 STRUCTURE AND MODIFICATION HISTORY . 14 Pre-Noachian . 14 Early Noachian Epoch .
    [Show full text]
  • Chryse Planitia As a Mars Pathfinder Land
    https://ntrs.nasa.gov/search.jsp?R=19950009770 2020-06-16T08:53:35+00:00Z View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NASA Technical Reports Server LPI TechnicalReport 9464 23 CHRYSE PLANITIA AS A MARS PATHFINDER LAND- creasing the information content of small-scale investigations dur- ING SITE: THE IMPERATIVE OF BUILDING ON PRE- ing short traverse lengths. VIOUS GROUND TRUTH. L. S. Crumpler. Department of Knowing the detailed questions that will be asked greatly in- Geological Sciences, Brown University,Providence RI 029 12, USA. crease the ability to design a successful experimental test: Viking Lander 1 raised detailed questions that Mars Pathfinder may be Introduction: Based on consideration of the geological char- designed and engineered specifically to address. For example, what acteristics of Chryse Planitia. the requirements for Mars Pathfinder are the dense, coarse, and pitted lithologies? What is the origin of landing sites, the nature of the mission, the scale of the observations the block distribution?Impact? Outwash? In situ weathering? What to be made, and the need to build outward from previous experience, is the grain size of the surface fmes, sand or silt? What is the a new mission to Chryse Planitia offers several advantages that are microstratigraphy of the fines? Is there a stable substrate in chryse difficult to ignore and offers a low-gamblehigh-return mission at lander scales of observation? Other regional geological issues scenario. Considering the need to ensure a successful mission, and remain: What is the geological unit of central Chryse, volcanic or to ensure the continued health of planetary exploration, the reasons sedimentary? Is there microscale evidence for standing water or for a new mission to Chryse Planitia are compelling.
    [Show full text]
  • Geologic History of Chryse Basin, Mars: New Crater Counts and Mapping Results; K.L
    LPS XXVII 1311 GEOLOGIC HISTORY OF CHRYSE BASIN, MARS: NEW CRATER COUNTS AND MAPPING RESULTS; K.L. Tanaka, U.S. Geological Survey, Flagstaff AZ 86001; [email protected] A complex sequence of erosional, depositional, and structural events that make up the geologic history of Chryse basin has been deciphered by photogeologic methods, including geologic/geomorphic mapping at 1:5,000,000 scale (partly revised from [I]) and new, more thorough crater counts (Table 1). Apparently, four distinct episodes of outflow-channel formation and associated basin sedimentation occurred from Late Noachran to Middle Amazonian time, interspersed by local emplacement of volcanic flows, structural deformation, and mass wasting. Episode 1: Late Noachian. Mawrth Vallis, perhaps the earliest outflow channel on Mars, as well as other minor channels locally dissected highland rocks (unit HNr; map units shown in [I]). Within Chryse basin, marginal highland rocks succumbed to mass wasting, forming mosaics of mesas separated by grooves and isolated knobs (many of which are preserved on local, topographic highs such as crater rims and older wrinkle ridges). Next, volcanism emplaced an early outcrop of ridged plains material (unit Hr) in southwestern Chryse basin. Episode 2: Early Hesperian. A thick sequence of lava flows (ridged plains material, unit Hr) buried Lunae Planum and southern Tempe Terra. Floods then washed across northern Lunae Planum, carving plateau tops (unit Hchs) and the broad, higher floor of Kasei Valles (unit Hchh); mass wasting soon degraded parts of the plateaus (unit Hrd). Perhaps at about the same time, precursory Simud, Tiu, and Ares Valles were cut through both highland rocks as well as ridged plains material in southern Chryse Planitia.
    [Show full text]